Transcript for Hillary and Bill Clinton Fire Back Against 2016 Critics

Thanks, Ron. Now, to the country's most powerful political couple. Bill and Hillary Clinton back in the spotlight in a big way this past week, when a top republican strategist raised questions about Hillary Clinton's health if she runs for president in 2016. It was the former president who fired back. And ABC's Jeff Zeleny has more from the white house. Things are heating up early, Jeff. They are, bianna. Good morning. President Obama has more than 2 1/2 years left in office. That's 977 days to be exact. But increasingly, it's bill and Hillary Clinton who are dominating the headlines in a way we haven't seen in a while. The Clintons are everywhere. The biggest tag team in politics. There's Hillary defending bill. My husband gave a lecture at Georgetown recently where he walked through the Numbers. Yes, a rising tide really did lift all those. Reporter: And bill defending Hillary. Now, they say she's really got brain damage. If she does, I must be in really tough shape because she's still quicker than I am. Reporter: In the past week alone, the Clintons made 14 public appearances. In speeches, at museum openings and even squeezing in time for the extended family. Campaigning for Chelsea's mother-in-law, who is running for congress in Pennsylvania. Barely a day passing by when they weren't making headlines. Hi, everybody. Reporter: Sometimes more than president Obama. So, is all this a prelude to a 2016 presidential run? She played coy in Barbara Walters' farewell appearance on "The view." Are you going to run? Well, I am running, around the park. Reporter: Republicans are following every word and striking back. On how secretary of state Hillary Clinton handled the attack on the U.S. Consulate in benghazi, Libya. And raising questions about her health. She had a serious health episode. This will be an issue in the 2016 race, whether she likes it or not. Reporter: Of course, we still don't know if she's running for anything. She likely won't make that decision until the end of the year. Now, the question surrounding Hillary Clinton's plans will only intensify when her book is released next month. But republicans have something else in mind. That special congressional committee investigating the benghazi attacks will get under way this summer, with her role as secretary of state back in the spotlight. Bianna? So much scrutiny, Jeff. But 14 appearances in 1 week for the couple. The Clintons are a big story that George stephanopoulos will be talking about this morning on "This week." And George joins us now. The right, the left, the center is talking about Hillary Clinton. I was struck by bill Collins that he wrote yesterday. Hillary wants to be president so people will stop talking about her. The Obama model, exactly. The Clintons are catnip for the media. There's no question about that. And part of the reason they're getting so much attention right now is because Washington is paralyzed, as well. Not a lot of news coming out of there. But there's a little more going on opinion number one, Karl rove. And his questions about Hillary Clinton's age and health. The republicans know she's unlikely to have significant opposition in the democratic party. So, they have to start their campaign early and in some ways make her old news by the time 2016 comes around. And the Clintons had to respond forcefully to this one because these questions about age and health always come up in presidential campaigns. They can be serious questions. They know they have to rebut this with real force. And that's what they did. And there's so much speculation on fresh faces. What's your idea of Julian Castro to join the cab innocent. It's the second time he asked him to be a part of the cabinet. Hillary Clinton got the nomination on the short list for vice president. Hard for democrats to win Texas. A hispanic on the party in 2016. It could be quite powerful. He is from Texas. And he would be 42 at the time. George will have much more on this topic coming up later on ABC's "This week."

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